and flexible electronic devices to harvest solar energysays Luyao Lu a graduate student in chemistry and lead author of a paper in the journal Nature Photonics that describes the result.
The standard mechanism for improving efficiency with a third polymer is by increasing the absorption of light in the device.
and the Advanced Light source at Lawrence Berkeley. ithout that it s hard to get insight about the structureyu says. hat benefits us tremendously. his knowledge will serve as a foundation from
Then by shining a light on these modified neurons via a tiny fiber optic cable inserted into the brain researchers can control the activity of the cells as well as their associated behaviors.
With the social neurons the behavior that was elicited depended upon the intensity of the light signal.
That is when high-intensity light was used the mice became aggressive in the presence of an intruder mouse.
When lower-intensity light was used the mice no longer attacked although they were engaged still socially with the intruder#either initiating mating behavior
and for minutes even after the light was turned off. The researchers could also use the light-activated neurons to stop the mice from engaging in particular behaviors.
For example if a lone mouse began spontaneously self-grooming the researchers could halt this behavior through the optogenetic activation of the social neurons.
Once the light was turned off and the activation stopped the mouse would return to its self-grooming behavior.
so that we could create new materials with the same kind of distributed light-sensing and processing abilities that they appear to have in their skinssays Naomi Halas a coauthor of the study published in PNAS
and director of Rice university s Laboratory for Nanophotonics. e know cephalopods have some of the same proteins in their skin that we have in our retinas so part of our challenge as engineers is to build a material that can see light the way their
and eventually to combine it with other new technologies that the squid skin team has developed both for sensing light
For example Halas and colleagues published a study in Advanced Materials in August about an aluminum-based CMOS-compatible photodetector technology for color sensing.
You can create materials by design. he researchers use a direct laser writing method called two-photon lithography to ritea three-dimensional pattern in a polymer by allowing a laser beam to crosslink
The parts of the polymer that were exposed to the laser remain intact while the rest is dissolved away revealing a three-dimensional scaffold.
#Detector could vastly improve night-vision goggles Monash University right Original Studyposted by Glynis Smalley-Monash on September 8 2014 Researchers have developed a light detector that could revolutionize chemical-sensing equipment and night-vision technology.
The detector which is interconnected based on the carbon atoms in graphene can sense light over an unusually broad range of wavelengths including terahertz waves between infrared
and microwave radiation where sensitive light detection is most difficult. e have demonstrated light detection from terahertz to near-infrared frequencies a range about 100 times larger than the visible spectrumsays Professor Michael Fuhrer of the School of Physics
The research could lead to a generation of light detectors that could see below the surface of walls
#Squid skin inspires eyelike photodetector Rice university rightoriginal Studyposted by Jade Boyd-Rice on August 27 2014the technology behind a new type of photodetector mimics the way squid likely sense colors.
Based on that hypothesis Bob Zheng a graduate student at Rice university set out to design a photonic system that could detect colored light.
The photodetector which sees colors in much the same way the human eye does uses an aluminum grating that can be added to silicon photodetectors with the silicon microchip industry s mainstay technology omplementary metal-oxide
The new device was created by researchers at Rice s Laboratory for Nanophotonics (LANP) and is described in a new study in the journal Advanced Materials.
Conventional photodetectors convert light into electrical signals but have no inherent color-sensitivity. To capture color images photodetector makers must add color filters that can separate a scene into red green and blue color components.
This color filtering is done commonly using off-chip dielectric or dye color filters which degrade under exposure to sunlight
Zheng s color photodetector uses a combination of band engineering and plasmonic gratings comb-like aluminum structures with rows of parallel slits.
which is a common technique in CMOS processing Zheng deposited a thin layer of aluminum onto a silicon photodetector topped with an ultrathin oxide coating.
Color selection is performed by utilizing interference effects between the plasmonic grating and the photodetector s surface.
and the width and spacing of the slits Zheng was able to preferentially direct different colors into the silicon photodetector
Light of a specific wavelength can excite a plasmon and LANP researchers often create devices where plasmons interact sometimes with dramatic effects. ith plasmonic gratings
You get this funneling of light into a concentrated area. The Office of Naval Research the Department of defense s National security Science and Engineering Faculty Fellowship Program and the Robert A. Welch Foundation supported the research.
and Technology Canadian Light source Inc. and University of Tennessee contributed to the study. Principal funding came from by the Global climate and Energy project the Precourt Institute for Energy at Stanford and by the US Department of energy.
#Chilly molecules pave way for ultracold science Yale university rightoriginal Studyposted by Jim Shelton-Yale on August 25 2014physicists have chilled molecules to almost absolute zero using lasers fired from an apparatus they built in the lab. The molecules
The technology uses lasers to simultaneously cool particles and hold them in place. magine having a shallow bowl with a little molasses in itdemille explains. f you roll some balls into the bowl they will slow down
and the bowl with molasses is created via laser beams and magnetic fields. ntil now the complicated vibrations and rotations of molecules proved too difficult for such trapping.
The process uses a dozen lasers each with a wavelength controlled to the ninth decimal point. f you wanted to put a picture of something high-tech in the dictionary this is
which is slowed by pushing on it with a laser. t s like trying to slow down a bowling ball with ping pong ballsdemille explains. ou have to do it fast
and do it a lot of times. he slowed molecules enter a specially shaped magnetic field where opposing laser beams pass through the center of the field along three perpendicular axes.
and his team to absorb specific nonvisible wavelengths of sunlight. e can tune these materials to pick up just the ultraviolet
and the near infrared wavelengths that then glow at another wavelength in the infraredhe says.
and identify out of place-place molecules on its surface using terahertz spectroscopy. They expect the finding to be important to manufacturers considering the use of graphene in electronic devices.
Hitting the combined material with femtosecond pulses from a near-infrared laser prompted the indium phosphide to emit terahertz back through the graphene.
and changes over time. he laser gradually removes oxygen molecules from the graphene changing its density
Laser pulses generated coherent bursts of terahertz radiation through a built-in surface electric field of the indium phosphide substrate that changed due to charge transfer between the graphene and the contaminating molecules.
and Masayoshi Tonouchi at Osaka s Institute of Laser Engineering are continuing to collaborate on a project to measure the terahertz conductivity of graphene on various substrates says Kono.
The research team presented this computational light field display on August 12 at the International Conference and Exhibition on Computer graphics and Interactive Techniques or SIGGRAPH in Vancouver Canada.
#Laser detects distant bombs with 99%accuracy Texas A&m University rightoriginal Studyposted by Ryan Garcia-Texas A&m on August 13 2014new laser technology makes it possible to identify explosives biological
The lasers travel long distances and identify dangerous materials present within powders that commonly act as carriers for explosive nitrates and lethal biological agents such as anthrax and ricin.
and the Proceedings of the National Academy of Sciences the technology involves beaming a high-powered laser onto a powder for an extremely short amount of time#about a trillionth of a second.
When laser light contacts the molecules present within the powder it experiences a scattering effect that can be analyzed to construct a sort of molecular ingerprintthat reveals its exact chemical makeup says Vladislav Yakovlev professor in the biomedical engineering department at Texas A&m University. s
but by taking advantage of the inherent properties of the targeted powder researchers have been able to dramatically amplify the resulting emission. n very simple terms we can take a powder shine a laser on this powder
which light is amplified. When a laser passes through the powder its wavelength is absorbed not fully.
Instead some of the light from the laser scatters and the path length increases because of this multiple scattering#something scientists refer to as the aman effect. his scattered light is emitted then from the powder in a strong diffuse form that is visually similar to a bright LED light.
It#s this extremely bright emission that can be collected from long distances. e get a large amount of energy into the system in a very short amount of time.
Yakovlev and colleagues have been able to increase the scattering efficiency by nine orders of magnitude meaning more light can be detected from greater distances.
which could beam a laser at the powder and collect the resulting signal with a powerful parabolic antenna so that the signal could then be analyzed
For example if you look at a galaxy you expect any explosions to roughly be in line with the underlying light you see from that galaxy
#See into living brain with lasers and nanotubes Stanford university rightoriginal Studyposted by Bjorn Carey-Stanford on August 7 2014by injecting carbon nanotubes into the bloodstream scientists can use near-infrared lasers to see blood flow in a living animal s brain.
The new technique which is almost completely noninvasive was developed for mice but could offer insight into human ailments such as strokes migraines and possibly Alzheimer s and Parkinson s diseases.
The researchers then shine a near-infrared laser over the rodent s skull. The light causes the specially designed nanotubes to fluoresce at wavelengths of 1300-1400 nanometers;
this range represents a sweet spot for optimal penetration with very little light scattering. The fluorescing nanotubes can then be detected to visualize the blood vessels structure.
Amazingly the technique allows scientists to view about three millimeters underneath the scalp and is fine enough to visualize blood coursing through single capillaries only a few microns across says senior author Hongjie Dai professor of chemistry at Stanford university.
Furthermore it does not appear to have any adverse affect on innate brain functions. he NIR-IIA light can pass through intact scalp skin
and is now a postdoctoral fellow at Harvard university. ll we have to remove is some hair. he techniqueâ reported in Nature Photonics could eventually be used in human clinical trials Hong says
but they also prevent light from passing through the cells o if we need to see individual cells within a large volume of tissue#within a mouse kidney for example
#Laser device sniffs out tiny traces of explosives University of California Berkeley rightoriginal Studyposted by Sarah Yang-Berkeley on July 24 2014mechanical engineers have found a way to dramatically increase the sensitivity of a light-based plasmon sensor.
The device works by detecting the increased intensity in the light signal that occurs as a result of this interaction. e think that higher electron deficiency of explosives leads to a stronger interaction with the semiconductor sensorsays study co-lead author Sadao
Because of this the researchers are hopeful that their plasmon laser sensor could detect pentaerythritol tetranitrate or PETN an explosive compound considered a favorite of terrorists.
The ability to increase the sensitivity of optical sensors traditionally had been restricted by the diffraction limit a limitation in fundamental physics that forces a tradeoff between how long
and in how small a space the light can be trapped. By coupling electromagnetic waves with surface plasmons the oscillating electrons found at the surface of metals researchers were able to squeeze light into nanosized spaces
but sustaining the confined energy was challenging because light tends to dissipate at a metal s surface.
The new device builds upon earlier work in plasmon lasers by Zhang s lab that compensated for this light leakage by using reflectors to bounce the surface plasmons back and forth inside the sensorâ##similar to the way sound waves
which work by detecting shifts in the wavelength of light Zhang says. he difference in intensity is similar to going from a light bulb for a table lamp to a laser pointer.
The technique is based on Fourier transform infrared spectroscopy, which provides information on how molecules vibrate.
Ogilvie and her research group developed an ultrafast laser pulse experiment that can match the speed of these reactions.
By using carefully timed sequences of ultrashort laser pulses, Ogilvie and coworkers were able to initiate photosynthesis
we have lots of great light absorbers and systems that can create charge separation, but it hard to maintain that separation long enough to extract it to do useful work.
the new method for enriching stable isotopes, called MAGIS (magnetically activated and guided isotope separation), needs little energy due to its use of low-powered lasers and permanent magnets.
But the light has to get there. A new one-step process to etch nanoscale spikes into silicon lets the maximum amount of sunlight reach a solar cell,
but the anti-reflection is limited to a specific range of light, incident angle, and wavelength, says Andrew Barron, professor of chemistry and of materials science and nanoengineering at Rice university.
Enter black silicon so named because it reflects almost no light. Black silicon is simply silicon with a highly textured surface of nanoscale spikes
or pores that are smaller than the wavelength of light. The texture allows the efficient collection of light from any anglerom sunrise to sunset.
Barron and graduate student Yen-Tien Lu, the study lead author, replaced a two-step process that involved metal deposition
This new form of solid stable light-sensitive nanoparticles called colloidal quantum dots could lead to cheaper and more flexible solar cells as well as better gas sensors infrared lasers infrared light emitting diodes and more.
-and p-type layers simultaneously not only boosts the efficiency of light absorption it opens up a world of new optoelectronic devices that capitalize on the best properties of both light and electricity.
#Scientists are first to detect exciton in metals University of Pittsburgh rightoriginal Studyposted by Joe Miksch-Pittsburgh on June 2 2014humans have used reflection of light from a metal mirror on a daily basis for thousands of years
but it also enables reflected light to be a nearly perfect replica of the incoming light.
The ability to detect excitons in metals sheds light on how light is converted to electrical
In other words it may be possible to control how light is reflected from a metal. The paper appears online in Nature Physics.
Guo and colleagues invented a special transducer that makes the light-to-sound conversion possible.
In this case it turns terahertz light into ultrasound waves and then transmits them. The transducer is made of a mixture of a spongy plastic called polydimethylsiloxane,
because it responds to the energy of individual terahertz light pulses, rather than a continuous stream of T-rays.
The study is published online in Nature Photonics. The National Science Foundation and the Air force Office of Scientific research funded the work e
or a home where the dry wall and siding store the electricity that runs the lights
The device uses a thumbnail-sized quantum cascade laser (QCL) as well as tuning forks that cost no more than a dime to detect very small amounts of nitrous oxide and methane.
That allows for far better detection of gases than more common lasers that operate in the near-infrared.
The technique called uartz-enhanced photoacoustic absorption spectroscopy (QEPAS invented at Rice university in 2002 by engineer Frank Tittel, Professor Robert Curl,
and is far better able to detect trace amounts of gas than lasers used in the past.
The laser beam is focused between the two prongs of the quartz tuning fork. When light at a specific wavelength is absorbed by the gas of interest
localized heating of the molecules leads to a temperature and pressure increase in the gas. f the incident light intensity is modulated,
then the temperature and pressure will be as well, Ren says. his generates an acoustic wave with the same frequency as the light modulation,
Kreidberg Bean and their colleagues used Hubble to precisely measure the spectrum of GJ 1214b in near-infrared light finding what they consider definitive evidence of high clouds blanketing the planet.
The nanoparticle is fluorescent in visible light and the nanotubes are fluorescent in the near-infrared.
or the first time we predicted their properties using quantum mechanics. he nanocrystals are about 3 nanometers wide by 500 nanometers longor about 1/1000th the width of a grain of sandmaking them too small to study with light microscopes
light in the universe may help reveal secrets about the earliest moments in its formation.
when the trajectory of light is bent by massive objects much like a lens focuses light.
Measurements of this ancient light have given already physicists a wealth of knowledge about the properties of the universe.
Tiny variations in temperature of the light have been mapped painstakingly across the sky by multiple experiments
Light is polarized when its electromagnetic waves are oriented preferentially in a particular direction. Light from the cosmic microwave background is polarized mainly due to the scattering of photons off of electrons in the early universe through the same process by
which light is polarized as it reflects off the surface of a lake or the hood of a car.
As molecules spin in space they emit light of very specific wavelengths or colors called mission lines. he precise wavelength is dictated by the composition and structure of the molecule.
Studying the emission lines observed by the SPIRE instrument allows astronomers to study the chemistry of outer space.
Comparing the spectra of light reflected from the peaks of those later craters may yield clues to the composition of the Moon'#lower crust
Using Moon Mineralogy Mapper data the researchers looked at the light reflected from each of the four central peaks.
The spectra of reflected light give scientists clues about the makeup of the rocks The spectra showed substantial differences in composition from peak to peak.
NASA'#Lunar Advanced Science and Exploration Research (LASER) program and the NASA Lunar Science Institute (NLSI) supported the research.
#Laser light creates hologram the width of a hair Purdue University rightoriginal Studyposted by Emil Venere-Purdue on December 9 2013researchers have created tiny holograms using a etasurfacecapable of the ultra-efficient control of light.
Laser light shines through the nanoantennas creating the hologram 10 microns above the metasurface. f we can shape characters we can shape different types of light beams for sensing
because the wavelength of light is too large to fit in tiny components needed for integrated circuits. Nanostructured metamaterials however are making it possible to reduce the wavelength of light allowing the creation of new types of nanophotonic devices says Vladimir M. Shalaev scientific director of nanophotonics at Purdue s Birck Nanotechnology Center
and professor of electrical and computer engineering. he most important thing is that we can do this with a very thin layer only 30 nanometers
and this is unprecedentedshalaev says. his means you can start to embed it in electronics to marry it with electronics. he layer is about 1/23rd the width of the wavelength of light used to create the holograms.
and control the routing of light in devices too tiny for conventional lasers. The researchers have shown how to control the intensity
and phase or timing of laser light as it passes through the nanoantennas. Each antenna has its own hase delayow much light is slowed as it passes through the structure.
Controlling the intensity and phase is essential for creating working devices and can be achieved by altering the V-shaped antennas.
Medical imaging could also benefit greatly as the dots show robust performance as fluorescent agents. ne of the problems with standard probes in fluorescent spectroscopy is that
and hit them with high-powered lasers you see them for a fraction of a second to upwards of a few seconds
A small change in the size of a quantum dot as little as a fraction of a nanometer##changes its fluorescent wavelengths by a measurable factor
and DNA. ingle crystals are the backbone of many things we rely onâ##diamonds for beauty as well as industrial applications sapphires for lasers
but the recipe can be applied to a variety of materials with potential applications in the fields of materials science photonics electronics
#Quantum wells flash light without magnets Spontaneous bursts of light from a solid block illuminate the unusual way interacting quantum particles behave
That opens up the possibility of making compact semiconductor devices to produce picosecond pulses of light. The researchers report their findings online in Scientific Reports.
Previous experiments showed the ability to create superfluorescent bursts from a stack of quantum wells excited by a laser in extreme cold and under the influence of a strong magnetic field both
Kono says the team didn t understand at the time why the wavelength of the burst changed over its 100-picosecond span.
Now they Do in the new results the researchers not only described the mechanism by which the light s wavelength evolves during the event (as a Fermi-edge singularity)
When pumped by a strong laser these quantum degenerate particles gathered energy and released it as light at the Fermi edge:
The researchers found the emitted light shifted toward the higher red wavelengths as the burst progressed. hat s cool about this is that we have a material we excite it with a 150-femtosecond pulse wait for 100 picoseconds
The findings may shed new light on how plants as well as other living organisms respond to environmental conditions.
and clunkyâ##if you wanted to cloak a car for example in practice you would have to completely envelop the vehicle in many layers of metamaterials in order to effectively hieldit from electromagnetic radiation.
or light waves could use the same principle as the necessary antenna technology matures. here are more applications for radio than for lightsays Eleftheriades. t s just a matter of technologyâ##you can use the same principle for light
and light is projected onto the resin to cure it in the shape of the related layer.
Such semiconductors are used often in lasers optics and infrared detectors. The National Science Foundation and USC funded the work.
Once an excited electron crosses over the interface from the material that absorbs the light to the material that will conduct the current it can't cross back giving it a direction. here's a small category of materials
because they have only been demonstrated with ultraviolet light and most of the energy from the sun is in the visible
and infrared spectrum. â#Finding a material that exhibits the bulk photovoltaic effect for visible light would greatly simplify solar cell construction.
as coins raining down on you with the different frequencies of light being like pennies nickels dimes and so on.
A quality of your light-absorbing material called its bandgap determines the denominations you can catchrappe says. he Shockley-Queisser limit says that whatever you catch is only as valuable as the lowest denomination your bandgap allows.
if you picked a lower denominationhe says etting your bandgap to catch only silver dollars is like only being able to catch UV LIGHT.
even though you're losing most of the energy from the UV you do get. s no known materials exhibited the bulk photovoltaic effect for visible light the research team worked to devise how a new one might be fashioned and its properties measured.
but with elements from the second material in key locations enabling it to absorb visible light. he design challengesays Peter K. Davies chair of the department of materials science and engineering as to identify materials that could retain their polar properties while simultaneously absorbing visible light.
Most light absorbing materials have a symmetrical crystal structure meaning their atoms are arranged in repeating patterns up down left right front and back.
The researchers used X-ray crystallography and Raman scattering spectroscopy to ensure they had produced the crystal structure and symmetry they intended.
and bandgap showing that they could indeed produce a bulk photovoltaic effect with visible light opening the possibility of breaking the Shockley-Queisser limit.
LED lightingâ##allowing for brighter more efficient lights. hese guidelines should permit the discovery of new and improved phosphors in a rational rather than trial-and-error mannersays Ram Seshadri a professor in the department of materials at University of California
which converts and mixes the blue light into the green-yellow-orange range of light. When combined evenly with the blue the green-yellow-orange light yields white light.
The notion of multiple colors creating white may seem counterintuitive. With reflective pigments mixing blue and yellow yields green;
which convert the higher energy blue light to lower energy yellow/orange light. o far there has been no complete understanding of
s LEDS become brighter for example as they are used in vehicle front lights they also tend to get warmer
Current incandescent light bulbs by comparison are at roughly 5 percent efficiency and fluorescent lamps are a little more efficient at about 20 percent. e have demonstrated already up to 60 percent efficiency in lab demosdenbaars says.
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